Focus stacking

At f/11, the DOF in this image of a Wolf Spider is very limited.

Combining 8 exposures, each taken at f/11, gives good DOF.

Focus stacking is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of field (DOF) than any of the individual source images (Johnson 2008, 336; Ray 2002, 231–232).

Getting sufficient depth of field can be particularly challenging in macro photography. Depth of field is normally increased by stopping down aperture (using a larger f number), but cannot be stopped down beyond a certain point without suffering from blurring due to diffraction. Focus stacking allows the depth of field of images taken at the sharpest aperture to be effectively increased. The images at right illustrate the increase in DOF that can be achieved by combining multiple exposures.

Focus stacking also offers flexibility, in that images with several different depth of fields can be generated in postprocessing and compared, and physically unrealizable images with nonplanar focus regions can be generated.

Other digital imaging techniques used to increase DOF include wavefront coding and plenoptic cameras.

Software

References

• Johnson, Dave. 2008. How to Do Everything: Digital Camera. 5th ed. New York: McGraw-Hill Osborne Media. ISBN 978-0071495806
• Ray, Sidney. 2002. Applied Photographic Optics. 3rd ed. Oxford: Focal Press. ISBN 0-240-51540-4

See also

• High dynamic range imaging (HDR)
• Image stitching
• Deconvolution microscopy

External links

• Online article by Rik Littlefield.
• Link directory Focus stacking (Extended Depth of Field).